Mechanical stirrer



2 Nov. 2, 1948. M. M. GRAFF 2,452,923

MECHANICAL STIRRER Filed Nov. 26, 1.946 2 Sheets-Sheet 2 INVENTOR M.M.GRAFF ATTORNEY Patented Nov. 2, 1948 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) Claims.

This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described, if patented, may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to me of any royalty thereon.

This invention relates to a mechanical stirrer for use in the preparation of fine suspensions, slurries, emulsions or solutions, such as solutions of soaps in water, waxes in oils, rosin size emulsions, slurries of potatoes, carrots, and the like in water, and in the disintegration of pharmaceutical products in solvents.

One object of this invention is to provide an improved stirrer which can be inserted through a relatively very small opening in the top of a flask or other vessel, and yet which can be expanded to many times the diameter of such opening so as to furnish rapid and effective agitation throughout the contents of the vessel.

It is a further object of this invention to provide an improved stirrer which is highly efllcient in agitating slurries, suspensions, and emulsions because of the cutting action of the rotating blades. v

It is also an object of this invention to provide an improved stirrer which is especially suitable for use in mixing and stirring food products as well as pharmaceutical or biological preparations where it is imperative that exposure to the air be reduced to a minimum, because this stirrer can be inserted in the mixing or dissolving vessel through a relatively very small opening, and because the blades are so designed, jointed, and secured as to permit freedom of action and adjustment to minimize the drawing in of air and the formation of a foam or froth.

I attain these objects by the device illustrated in the following drawing, in which Figure 1 is a vertical view of the collapsed stirrer; Figure 2, a view of the expanded stirrer; Figure 3, a view of the expanded and twisted stirrer; Figure 4, a plan view of the ball and socket joints for the lower ends of the blades: Figure 5, a vertical section of the ball and socket joints for the upper ends of the blades; and Figure 6, a vertical view of a blade and attached coupling balls.

Similar numerals refer to similar parts throughout the several views.-

The stirring device comprises a shaft 1, which may be solid or hollow, secured at its lower end to a disc Ill. The upper end of the shaft, may be fastened to the shaft of an electric motor or a rotating countershaft. Surrounding a portion of the shaft I is a, sleeve 2 which is free to slide thereon. This sleeve is provided at its upper end with fastening means, such as set-screw I in flange 3. The lower end of the sleeve is secured to or integral with a disc II.

The beater elements comprise flat strips or blades 5, preferably of springy metal, such as spring steel, stainless steel, brass, or copper. While four blades are shown, it is understood the device will operate satisfactorily with two, three, or more blades. The edges of the blades may be blunt or sharp, or they may have notched edges to facilitate the disintegration of the solid material which is to be slurried or dissolved. Ha ksaw blades or sections of a band-saw blade may be used. The ends of the blades are connected through ball and socket joints to the discs Ill and H. For this purpose the lower end of each blade 5 is provided with a ball 9, attached through pin 6 to the blade. A second pin 1 and ball 8 are attached to the upper end of the blade. The upper balls I rest in sockets in upper disc 12, and are secured therein by plate II, as shown in detail in Figure 5. The lower balls 9 rest in sockets in lower disc It, being held therein by plate l3. Other flexible or universal joints may be substituted for the ball and socket joint. For example, chain links may be used. One may employ hooks secured to the sleeve or to the shaft at one end and hooked through holes near the ends of the blades. Ii desired, a plate with four slots may be secured to the upper surface of disc Hi, to receive the four pins 8 and to limit lateral movement thereof. A similar plate may be placed upon the lower face of disc i2.

There is sometimes a tendency, especially on the larger models, for the slurry or solution to creep up the shaft inside the sleeve, and thereby cause sticking of the sleeve on the shaft. This can be avoided by constructing the sleeve with a gland or stufllng box at the lower end just below the point where the blades are attached. This should be adjusted to give a snug but not a tight fit around theshaft; so that it will not require too much force to slide the sleeve on the shaft, and yet prevent creeping of the slurry up inside the sleeve.

It will be noted that the blades are free to turn atboth ends, to a substantial extent, due to their attachment through a. ball and socket or link joint. This freedom of action assists in avoiding the whipping up of a foam or froth, since the blades are free to conform to the currents in the liquid or slurry being stirred, and therefore do not draw air into the liquid.

Another advantage of the invention is that the sleeve can be turned on the shaft, after expansion of the blades, to give the twist indicated in Figure 3. This arrangement is especially efficient in disintegrating solids to form slurries or solutions. As the stirrer rotates, the rough edges of the blades stay in contact with the chunks of solid for a longer time than when the blades are merely bowed out. There results more rapid disintegration of the solid material.

Having thus described my invention, I claim:

1. A stirrer for liquids and liquid-solid suspensions comprising a rotatable shaft, a member movable along said shaft and rotatable about the axis of said shaft, a number of stirring blades having their lower ends operably connected to the lower end of the shaft and having their upper ends operably connected to the lower end of said member, and means for securing the said member at a selected position along said shaft and in which each blade is operably connected, at its upper end, to the lower end of said member, as recited, through a ball and socket joint the upper end of each blade being free to pivot in the socket in a plane longitudinal to the axis of the shaft upon lowering the movable member to bow the stirring blades outwardly, and being free to pivot in the socket about an axis longitudinal to the upper end of the blade upon turning the movable member about the axis of the shaft to twist the blades.

2. A stirrer for liquid-s and liquid-solid suspensions comprising a rotatable shaft, a member movable along said shaft and rotatable about the axis of said shaft, a number of stirring blades having their lower ends operably connected to the lower end of the shaft and having their upper ends operably connected to the lower end of said member, and means for securing the said member at a selected position along said shaft, and in which the upper end of each blade is so operably connected to the lower end of raid member through a flexible joint having a rotatable element that permits the said upper end of the blade to be turned about its own longitudinal axis and permits the upper end of each blade to pivot in the joint in a plane longitudinal to the axis of the shaft.

3. A stirrer for liquids and liquid-solid suspensions comprising a rotatable shaft, a member movable along said shaft and rotatable about the axis of said shaft, a number of stirring blades having their lower ends operably connected to the lower end of the shaft and having their upper ends operably connected to the lower end of said member, and means for securing the said member at a selected position along said shaft and in which the upper end of each blade is operably connected. as recited, to the lower end of said member through a universal joint.

4. A stirrer for liquids and liquid-solid suspensions comprising a rotatable shaft, a member movable along said shaft and rotatable about the axis of said shaft, a number of stirring blades having their lower ends operabLv connected to the lower end of the shaft and having their upper ends operably connected to the lower end of said member, and means for securing the said member at a selected position along said shaft and in which the upper end of each blade is operably connected, as recited, to the lower end of said member through a ball and socket joint, the ballbeing attached to the blade end, said member having attached thereto means provided said socket the upper end of each blade being free to pivot in the socket in a plane longitudinal to the axis of the shaft upon lowering the movable member to bow the stirring blades outwardly, and being free to pivot in the socket about an axis longitudinal to the upper end of the blade upon turning the movable member about the axis of the shaft to twist the blades.

5. A stirrer for liquids and liquid-solid suspensions comprising a rotatable shaft, a member movable along said shaft and rotatable about the axis of said shaft, a number of stirring blades having their lower ends operably connected to the lower end of the shaft and having their upper ends operably connected to the lower end of said member, and means for securing the said member at a selected position along said shaft and in which the lower end of each blade is operably connected, as recited, to the lower end of the shaft through a flexible joint having a rotatable lement that permits the said lower end of the blade to be turned about its own longitudinal axis and permits the lower end of each blade to pivot in a plane longitudinal to the axis of the shaft.

6. A stirrer for liquids and liquid-solid suspensions comprising a rotatable shaft, a member movable along said shaft and rotatable about the xis of said shaft, a number of stirring blades having their lower ends operably connected to the lower end of the shaft and having their upper ends operably connected to the lower end of said member, and means for securing the said member at a selected position along said shaft and in which the upper end of each blade is operably connected, as recited, to the lower end of said member through a flexible joint having a rotatable element that permits the said upper end of the blade to be turned about its own longitudinal axis. and in which the lower end of each blade is likewise connected through a like flexible "oint to the lower end of said shaft.

'7. A collapsible stirrer for liquids and liquidsolid suspensions comprising a rotatable shaft, a member movable along said shaft and rotatable about the axis of said shaft, means for securing the said member at a selected position along said shaft, a coupling member fixed upon the shaft, a number of stirring blades of spring metal having t eir lower ends operably connected to the coupling member and their upper ends operably connected to the said movable member, each blade being connected as aforesaid to the movable member and the coupling member through a pivot link permitting the turning of each blade end about its own longitudinal axis. and turning movement of each blade end in a plane that is longitudinal t the axis of the shaft whereby, upon lowering he movable member the blades are caused to bow outwardlv. and upon raising said movable member t e blades are retracted toward the axis of the shaft and caused to lie longitudinal thereto, and whereby upon turning the movable member about the axis of the shaft the blades are twisted.

8. The device defined in claim '7, in which each flexible joint comprises a universal joint.

9. The device defined in claim 7 in which the gamma 5 first said flexible joints each comprises a ball attached to the blade and and a socket formed in an elenfint joined to the shaft end.

10. The device defined in claim 7 in which the second said flexible joints each comprises a ball attached to the blade end and a socket formed in an element joined to the sleeve end.

MORRIS M. GRAFF.

REFERENCES CITED The following references are of record in the file of this patent:

Number 7 1,195,839 1,417,982 2,079,272

Number 6 UNITED STATES PATENTS Name Date Moses Aug. 22, 1916 Fitzpatrick May 30, 1922 Arndt May 4, 1937 FOREIGN PATENTS Country Date Great Britain July 24, 1924 Germany July 18, 1930 

